The Influence of Illumination Direction on the Pictorial Reliefs of Lambertian Surfaces

In order to assess the influence of illumination direction on shape constancy, we studied the pictorial relief of computer images of globular 3-D objects. We used two globally convex objects, one with a furrow and one with a dimple. Observers adjusted local surface attitude probes at 200–250 different locations in the image such that they seemed to lie on the pictorial surface. We manipulated the viewing direction and the illumination direction in a 2times2 orthogonal design. Viewing directions were chosen such that the image contained only a few, or no, contour singularities. Changes in the illumination direction were found to induce systematic changes in the settings for both viewing directions. Effects were especially pronounced for images that had no contour singularities. The results showed that a change in the illumination direction can change the local shape of the pictorial relief in addition to the bas-relief ambiguities of scaling and shearing in depth. We found that concavities in the pictorial relief are associated with the darker areas in the image. The deviation from shape constancy cannot be explained by bas-relief ambiguity since the required transformation between the shapes is nonlinear.

[1]  J. Koenderink,et al.  Light Source Dependence in Shape from Shading , 1997, Vision Research.

[2]  Pascal Mamassian,et al.  Categorical Local-Shape Perception , 1996, Perception.

[3]  H. Bülthoff,et al.  Depth Discrimination from Shading under Diffuse Lighting , 2000, Perception.

[4]  J. Todd,et al.  Effects of changing viewing conditions on the perceived structure of smoothly curved surfaces. , 1996, Journal of experimental psychology. Human perception and performance.

[5]  J. P. Dufour,et al.  Singularités et photographies de surfaces , 1992 .

[6]  J. Koenderink,et al.  The singularities of the visual mapping , 1976, Biological Cybernetics.

[7]  D. Kersten,et al.  Illumination, Shading and the Perception of Local Orientation , 1996, Vision Research.

[8]  J T Todd,et al.  Ambiguity and the ‘Mental Eye’ in Pictorial Relief , 2001, Perception.

[9]  J. Koenderink,et al.  Surface perception in pictures , 1992, Perception & psychophysics.

[10]  Donald D. Hoffman,et al.  Salience of visual parts , 1997, Cognition.

[11]  H H Bülthoff,et al.  A Prior for Global Convexity in Local Shape-from-Shading , 2001, Perception.

[12]  Andrea J. van Doorn,et al.  Ecological optics and the creative eye , 2002 .

[13]  J. Koenderink,et al.  Perception of local shape from shading , 1993, Perception & psychophysics.

[14]  J. Koenderink,et al.  Perturbation Study of Shading in Pictures , 1996, Perception.

[15]  David J. Kriegman,et al.  The Bas-Relief Ambiguity , 2004, International Journal of Computer Vision.

[16]  J. Koenderink,et al.  Illuminance critical points on generic smooth surfaces , 1993 .

[17]  Chris Christou,et al.  Shape Constancy in Pictorial Relief , 1996, Object Representation in Computer Vision.